Preheat the oven to 180°C/gas mark 4. Put the breadcrumbs, horseradish, chopped dill and olive oil in a food processor and whizz until well blended, then season.
Place the salmon, skin-side down, on a lightly greased baking tray and cover with the breadcrumb mix, using your hands to press it down. Bake for 20-25 minutes until the crust is lightly golden and the salmon is just cooked. Transfer to a platter and garnish with lemon slices and dill sprigs.